The cell is the basic unit of life and comprises a variety of subcellular compartments including, for example, the organelles. An organelle is a structural component of a cell that is physically separated, typically by one or more membranes, from other cellular components, and which carries out specialized cellular functions. Organelles and other subcellular compartments vary in terms of, inter alia, their composition and number in cells derived from different tissues, among normal and abnormal cells, and in cells derived from different species. Accordingly, organelles and other subcellular compartments, and macromolecules specifically associated therewith, represent novel targets for the development of agents that specifically impact, respectively, a particular tissue within an animal, abnormal (diseased) but not normal (healthy) cells, or cells from an undesired species but not cells from a desirable species.
For example, members of the Bcl-2 family of proteins (discussed in more detail infra) associate with the outer membranes of mitochondria and with other cellular membranes. The translocation of Bcl-2 proteins from one intracellular position to another occurs during apoptosis, a process by which some abnormal (e.g., pre-cancerous) cells are directed to undergo programmed cell death (PCD), thus eliminating their threat to their host organism. Means for monitoring the accumulation of Bcl-2 proteins in various subcellular compartments, or their translocation from one intracellular location to another, would allow identification of agents designed to impact apoptosis, and to assay the effects of such agents in cells.
As another example, cytoplasmic cellular hybrids (cybrids) comprising the nucleus of one cell type and organelles (mitochondria) from another cell type have been prepared. Experiments with such cybrids have demonstrated that cellular defects associated with diseased cells are transferred with cytoplasmic elements (mitochondria) from diseased cells to cybrids. Diseases that have been demonstrated to have a cytoplasmic component in this manner include Alzheimer's disease and Parkinson's disease (Swerdlow et al., Neurology 49:918-925, 1997; Swerdlow et al., Annals of Neurology 40:663-671, 1996). Means for monitoring intracellular processes during the formation of cybrids, or for comparing intracellular processes between cybrids that have a common nuclear background but that differ according to the sources of donor cytoplasm as their sources of mitochondria, would allow one to study the mechanisms of such processes and to identify agents that impact such processes.
By way of further example, it is possible to develop antibacterial agents by taking advantage of the fact that bacterial cells comprise structures (e.g., cell walls) that are not present in eukaryotic cells, and by developing agents that specifically impact these structures. In contrast, it has been more difficult to develop agents to treat diseases and disorders resulting from eukaryotic parasites of mammals including humans, in part because of the fact that many cellular features of such parasites have structural similarities to homologous structures found in the host's cells; as a result, any agent that negatively impacts a cellular component of such a parasite is also likely to have a negative effect on the analogous component of the eukaryotic host cells.
There is thus a need for methods and compositions that allow for the rapid and detailed monitoring of processes within subcellular compartments and macromolecules associated therewith. Further, there is a need for methods and compositions for identifying and screening for agents that impact such processes in specific instances.
One objective of the present invention is to provide methods and compositions for monitoring and assaying processes within subcellular compartments and macromolecules associated therewith. When such processes are associated with particular diseases and/or disorders, the invention may be used in a predicative, diagnostic or prognostic modality.
Another objective of the present invention is to provide methods for screening for and identifying agents that impact organelles and other subcellular compartments in specific ways. When such agents are specific for undesirable abnormal cells, or for the cells of an undesirable parasites, they are expected to have remedial, therapeutic, palliative, rehabilitative, preventative, prophylactic or disease-impeditive effects on patients comprising such undesirable cells.
The present invention fulfils these needs and realizes these and other objectives. Other advantages of the invention are apparent from the disclosure.